Electrical switching apparatus



Nov. s, 1960 R. J. WAGNER ET AL 2,959,727

ELECTRICAL SWITCHING APPARATUS 2 Sheets-Sheet l Filed May 24, 1957 m MGN Y E ONG N TAA Dn N LW O m T mRJ M TT R nlv E L B LO ER Y nD Nov. 8, 1960 R. .1. WAGNER ETAL 2,959,727

ELECTRICAL SWITCHING APPARATUS Filed May 24, 195'? 2 Sheets-Sheet 2 F I G. 3

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i flo? NVENTOR '06 95 9' 98 ELLIOT R. LANG BY ROBERT .LWAGNER MMM ATTORNEY.

nited States jillatent@nice ELECTRICAL SWITCHING APPARATUS Robert J. Wagner, Feasterville, Pa., and Elliot R. Lang, Pennsauken, NJ., assignors to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Filed May 24, 1957, Ser. No. 661,495

14 Claims. (Cl. 321-48) The present invention pertains to electrical switching apparatus of the type generally referred to as synchronous converters. More specifically, the present invention is concerned with the type of synchronous converter in which a movable contact member is caused to alternately engage and disengage stationary contacts.

A general object of the present invention is to provide a new and improved converter which is relatively insensitive to Shock, vibration, and position of mounting.

Another object of the present invention is to provide a new and improved converter which is capable of operation over a wide frequency range.

Still another object of the present invention is to provide a new and improved armature and Contact structure which eliminates contact bounce or rebound of the contacts occurring after the initial contact closure.

A further object of the present invention is to provide a converter in which the response of the armature to the armature driving signal is such that there is negligible switching or transfer time between the engagement and disengagement of the respective contacts and a relatively mall phase lag between the armature motion and the rmature driving signal.

A still further object of the present invention is to provide a vibrating synchronous converter in which posi- Itive rapid armature movement is achieved without the use of a permanent magnetic structure.

The various objects of the present invention are achieved by means of structure employing a rigid lightweight armature assembly pivoted at its center of gravity on a torsion angle pivot. The armature assembly comprises a thin walled tubular member carrying at one end a flat magnetic slug which is positioned in a narrow gap between a pair of electro-magnets wound on saturable cores. The tubular armature member carries a contact at its other end. This contact extends from the tubular member between a pair of stationary contacts each comprising a pair of resilient wire contacts. Means are provided for alternately energizing the electro-magnets to cause the armature assembly Contact to alternately engage and disengage the stationary contacts as the ferromagnetic slug is alternately attracted to the respective electromagnets.

A better understanding of the present invention may be had from the following description read with reference to the accompanying drawings of which:

Fig. 1 is a front elevation of a preferred embodiment of the present invention;

Fig. 2 is -a partial side elevation of the embodiment of the present invention shown in Fig. 1 taken in section on the line 2-2;

Fig. 3 is an end elevation of the embodiment of the present invention as shown in Fig. 1 taken in section on the line 3 3;

u Fig. 4 is an exploded perspective view of certain elements of the embodiment of the present invention shown in Figs. 1, 2, and 3; and

' Fig. 5 is a diagram of the electrical circuitl of the embodiment of the present invention shown in Figs. 1,

2, and 3.

Referring now to Figs. 1 through 4, there is shown an embodiment of the present invention which is adapted to provide double pole, double throw, synchronous switching. This embodiment utilizes two separate synchronous converter units designated 1 and 2. These units have interconnected magnetic driving means 3 and 4 and a common stationary contact assembly 5, all housed in a casing 6. The casing 6 has a cover 7 which is adapted to be supported on a ledge 8 in the case 6 and sealed in place thereon by means of an epoxy resin. The casing 6 is adapted for mounting by means of the mounting holes 11, 12, and 13.

Since the converter units 1 and 2 are identical in construction, only the structural details of the unit 1 will be described except where the structure of the unit 2 is necessary to the explanation of the operation of the embodiment illustrated in the drawings which is a double pole, double throw, synchro-nous switch. The converter unit 1 has an armature assembly generally designated 15 which comprises a rigid thin walled tubular member 16 having a flat T-shaped slug of ferromagnetic material 17 welded to it at its one end and a contacting member 1S projecting from its other end. The contacting member 1% is overlayed with platinum iridium to provide long lasting contact operation. The contacting member 18 is held in the tubular member 16 by means of an epoxy resin indicated as 19. Accordingly, the contacting member 18 is insulated electrically and thermally from the tubular member 16.

The ferromagnetic slug 1'7 of the armature assembly 15 is positioned in a narrow air gap 21 between a pair' The electromagnets 22V of electromagnets 22 and 23. and 23 comprise a pair of coils 24 and 25 wound on E-shaped ferrite cores 26 and 27 respectively. The electromagnets 22 and 23 are clamped in and bonded by an epoxy resin to a magnet frame assembly 29 which is fastened to the case 6 by means of the screws 31 and 32. The magnet frame assembly 29 includes a pair of pivot supports 33 and 34 for the armature assembly pivot 36. The pivot 36 is a torsion angle pivot which extends through an opening 37 in the tubular member 16 of the armature assembly 15 and mounts in the pivot supports 33 and 34. The torsion angle pivot 36 is secured in the pivot supports 33 and 34 by means of an epoxy.

resin indicated as 41 and 42. The armature assembly 15 is also fastened to the torsion angle pivot by means of an epoxy resin indicated as 43. It should be noted that the pivot opening 37 in the tubular member 16 of the armature assembly 15 is located so that the center of gravity of the armature assembly 15 is at the intersection of the faces of the planes of the pivot.

Referring now to the stationary contact block assembly 5, this assembly includes a Contact block 44 which is fastened to the casing 6 by means of the screws 45 contacts 52 and 53 and the converter unit 2 has the` stationary contacts 54 and 55. Each of the stationary" contacts comprises a pair of resilient AWire contacts formed;

at the ends of U-shaped pieces of platinum iridium wire. The contacts are clamped and spot welded in the fold of a U-shaped contact clamping strip'and" extend through an opening therein. Thus, the contacts 52 and 53of Patented Nov. 8, 1960v the converter unit 1 are clamped in the U-shaped clamping strip 56 and 57 and the contacts 54 and 5S of the converter unit 2 are clamped in the U-shaped clamping strip 58 and 59.

The clamping stn'p 56 which holds the contact 52 of the converter unit 1 and the clamping strip 5-8 which holds the contact 54 of the converter unit 2 are welded to opposite ends of a T-shaped contact hinge 61. Similarly, the clamping strip 57 which holds the contact 53 of the converter unit 1 and the clamping strip 59 which holds the contact 55 of the converter unit 2 are spot welded to opposite ends of a T-shaped contact hinge 62. The contact hinges 61 and 62 are made of stainless steel strips bent around hinge spacers 63 and 64 respectively. The contact 52 of the converter unit 1 and the contact 54 of the converter unit 2 are electrically common and connection is made to these contacts through the hinge spacer which has a lead 65 welded thereto which passes through an opening in the contact hinge at kits U-shap'e to bend. Similarly, the Contact 53 of the converter 1 and the contact 55 of the converter unit 2 are electrically common and connection is made thereto by means of a lead 67 spot welded to the spacer 64 which passes through an opening in the U-shaped bend in the contact hinge 62.

The contacts, contact arms, contact hinges, contact spacers, and electrical leads thereto constitute sub-assemblies which can be pre-assembled before mounting in the contact block. The ltwo contact sub-assemblies are clamped in a channel cut in the contact block 44 and are insulated therefrom by means of a pair of E-shaped mica insulators 73 and 74. As shown, the portions of the contact block 44 between the corner posts 47 and 49 and the adjacent channel wall are cut away to make the sections 75 and 76 of the channel wall deectable. After the contact subassemblies have been inserted into the channel, the portions ofthe channel wall 75 and '76 are forced against the contact sub-assemblies by means of 4the screws 77 and 78 which are threaded into the corner posts 47 and 49. In this manner, the contact sub-assemblies are clamped to the contact block 44. It should be noted, that the contact hinges 61 and 62 are so constructed that the contact clamping strips 56, 57, 58, Iand 59 are biased against the adjacent inner walls of the corner posts 47, 49, 4S, and 51 respectively of the contact blocks 44. The stationary contacts are then adjusted relative to the movable contacts of the converter units 1 and 2 by means of the contact adjustment screws 79, S0, 81, and 82 which are threaded in the corner posts of the contact block 44. Each of the contact adjustment screws has a fused glass insulating tip to insulate it electrically from the contact circuit. The contact adjustment screws 79, 80, 81, and 82 lock plates 83, 84, 85, and Se, respectively, which lock them in position once contact adjustment is made. Contact adjustment may be made by removing the screws 87, 88, 89, and 90 in the side of the casing 6.

In addition to the other figures of the drawings, reference should be had to Fig. 5 which is an electrical circuit of the embodiment of the present invention shown in those other figures. As shown, the stationary contacts 53 of the converter unit 1, and the stationary contact 55 of the converter unit 2 are electrically common and are connected to a common terminal by means of the lead 67. This common terminal is the bulkhead receptacle 91 which passes through a hole in the side of the casing 6 and is secured therein by means of a nut 92. The stationary contact 52 of the converter unit 1 and the stationary contact 54 of the converter unit 2 are also electrically common and are connected through a lead 65 and a resistor 93 to ground. Ground in the embodiment of the present invention shown in Figs. l through 4 is the lug 94 which is soldered to the bulkhead receptacle 91. For clarity, the resistor 93 is not shown in Fig. 1 and is shown only in dotted outline in Fig. 2. It is, however, fully shown in Fig. 3.

Connection to the moving contacts of the converter 4 units land 2 are also made by means of bulkhead receptacles. Thus, the bulkhead receptacle is provided for connection to the moving contact 18 of the converter unit 1. The receptacle 95 passes through a hole in the side of the casing 6 and is secured therein by means of a nut 96. The connection between the moving contact 18 and the bulkhead `rceeptacle 95 is by means of a lead 97 which passes from the receptacle 95 through -a hole in the side of the tubular member 16 and then coaxially through the center of the tubular member 16 to the contact 18. In this manner, the tubular member 16 provides shielding for the lead 97. A bulkhead receptacle 98 is provided for connection to the moving contact 99 of the converter unit 2. The receptacle 98 passes through a hole in the side of the casing 6 and is secured therein by means of a nut 101. The connection between the bulkhead receptacle 98 and the contact 99 of the converter unit 2 is made by means of a lead 102 which passes through an opening in the tubular member of the armature assembly of the converter unit 2 and then coaxially through that member to the contact 99. The bulkhead receptacles 91, 95, and 98 are adapted to receive coaxial fittings for connecting the converter units into a circuit. u The driving circuit for the converter units 1 and 2 includes the diodes 104 and 105 which are mounted on shelves on the exterior of the casing 6 at its ends. The diodes 104 and 105 are mounted on the casing 6 by means of their mounting studs 106 and 107 respectively. The diode mounting studs 106 and 107 extend through holes in the casing shelves and are held therein by means of nuts 108 and 109, respectively. The diode 104 is insulated from the casing 6 by means of the washers 111 and 112 and the spacing washer 113. Similarly, the diode is insulated from the casing 6 by means of the washers 114 and and the spacing washer 116. A tie lug 117 iS inserted between the diode 104 and the washer 111 to connect the diode 104 into the converter driving circuit. Similarly, a tie lug 118 is inserted between the diode 105 and the washer 114 to connect the diode 105 into the converter driving circuit.

The mounting studs 106 and 107 of the diodes 104 and 105 are the terminals of the conventer driving circuit andl are adapted to be connected to a suitable source of alternating current having the desired converter driving frequency. The converter driving circuit can be traced from the terminal 106 through the coil 25 of the converter unit 1, the conductor 120, the coil 119 of the converter unit 2, and the diode 105 to the terminal 107. The converter driving circuit can also be traced from the terminal 107 through the coil 121 of the converter unit 2, the conductor 122, the coil 24 of the converter unit 1, and the diode 104 to the terminal 106. Thus, when the polarity of the alternating converter driving signal is such that the .terminal 106 is positive with respect to the terminal 107, the coil 25 of the converter unit 1 is energized, attracting the armature assembly of the converter unit 1 1 thereto causing the contact 18 to disengage the contact 53 and to engage the contact 52. Simultaneously, the coil 119 of the converter unit 2 is energized, causing the ferromagnetic slug on its armature assembly to be attracted thereto causing the contact 99 to disengage the contact 54 and to engage the contact 55. During the next half cycle of the converter energizing current, when the terminal 107 is positive with respect to the terminal 106, the coil 121 of the converter unit 2 is energized, causing the armature of the converter unit 2 to be attracted thereto, and thus causing the contact 99 to disengage the contact 55 and to engage the contact 54. Simultaneously, the coil 24 of the converter unit 1 is energized, causing its armature assembly to be attracted thereto and thus causing the contact 18 to disengage the contact 52 and to engage the contact 53. Thus, the converter unit 1 is adapted to switch the input to the terminal 95 first through the resistor 93 to ground then to the terminal 91. Simultaneously, the converter unit 2 is adapted to switch the essere?" input to the terminal 98 to the terminal 91 then through the resistor 93 to ground. This switching operation is carried on synchronously at the frequency of the alternating signal applied across the terminals 106 and 107.

Many features of the present invention cooperate to provide improved converter operation. The use of a low mass rigid balanced armature assembly provides rapid response to the magnetic driving forces and little response to vibration and also makes the converter insensitive to its moun-ting position. The mass of the converter armature is made low and rigidity retained by the use of a thin walled tubular member for the body of the armature asseimbly. The rigidity of the armature structure helps to reduce the phase lag between `the armature motion and the armature driving signal and eliminates any spurious bending along the armature which interferes with the positive motion of the moving armature contact as can occur in flat reed converters. The use of the torsion angle pivot provides a positive pivot location, zero friction, plus the return of the armature to a zero position in the absence of excitation. In addition, the low gradient of the torsion angle pivot acts to make the armature more responsive to the magnetic driving forces acting upon it rather than response to vibratory effects.

The diode rectifiers in series with the converter driving magnets provide two alternating magnetic attractions of the armature per cycle of alternating current excitation without the use of a polarizing permanent magnet. The alternately energized electromagnets are wound on ferrite cores that are designed to saturate rapidly. In this respect, it has been found advantageous to satur-ate the nonmoving portion of the armature driving system rather than the moving portion. Since the ferrite cores saturate rapidly, the converter is relatively insen-sitive to large changes in the converter driving signal which might otherwise cause poor contacting, excessive contact wear, and contact bounce. The armature assembly has been designed so that its center f gravity is close to the end of jthe armature assembly which carries the slug of ferromagnetic material.

' driving magnets may be made relatively small, allowing rapid armature response and a maximum magnetic pull While still providing a relatively large arc of travel for the In this manner, the gap between the armature contact.

The novel design of the stationary contact structure provides efficient long lasting electrical contacting without contact bounce. Due to the natural disymmetry of the wire contact pieces which make up each of the stationary contacts, one side contact wire is picked up by the moving contact just before its mate, thereby giving a step increase in gradient to absorb the energy of the moving contact. In addition, a slight oifset of adjacent contact wires permits a greater range of adjustment than a single wire contact. The use of a short length of resilient wire for the contacts provides a minimum mass and the high natural frequency required to follow the motion of the moving contact. Further, an ideally shaped contact surface of small radius is easily obtained by simply bending the end of the wire contact without special coining, thus obtaining the high contact pressure generally associated with small radius contact surface. Still further, the small radius of the contact movement insures a large amount of contact wipe.

Having now described the invention, that which is claimed as new and which is desired to secure by Letters Patent is:

1. An electrical switching means comprising, in combination, a rigid balanced armature pivoted at its center of gravity on a frictionless pivot, one end of said armature being disposed between a pair of satura-ting electromagnets, means for alternately supplying unidirectional electrical energy to the respective electromagnets and thereby to alternately attract to said electromagnets said end of the armature, and a pair of contacts, the other end of said armature being disposed between said pair of cond tacts and adapted to alternately engage and disengage respective ones of said pair of contacts as the rst mentioned end of said armature is alternately attracted to said electromagnets.

2. An electrical switching means comprising, in combination, a pair of saturating electromagnetic means separated by a gap, means for alternately energizing said electromagnetic means with unidirectional electric current, a rigid armature pivoted at its center of gravity on a torsion angle pivot, said armature carrying at one end a slug of ferromagnetic material, said slug being disposed in the gap between said pair of electromagnetic means, said armature carrying on its other end -a contact member, and a pair of resilient contacts, said contact member being disposed between said pair of resilient contacts and adapted to alternately engage and disengage said respective ones of said pair of resilient contacts as said magnetic slug is alternately attracted to the respective electromagnetic means.

3. An electrical switching means comprising, in combination, a rigid balanced armature pivoted at its center of gravity, said armature comprising a thin walled tube carrying at one `end of a flat slug of ferromagnetic material and at the other end a contacting member, a pair of saturating electromagnets, the ferromagnetic slug on said armature being positioned in a gap between said electromagnets, means for alternately supplying unidirectional electrical energy to the respective electromagnets to cause the attraction to said magnets of said slug as they are alternately energized, and a pair of contacts, the contacting member on said armature being positioned between said contacts to alternately engage and disengage respective ones of said contacts as the slug on said armature is attracted to respective ones of said electromagnets.

4. An electrical switching apparatus comprising, in combination, a lightweight rigid armature assembly, said armature assembly comprising a tubular member carrying at one end a flat T-shaped slug of ferromagnetic material and at the other end a contacting member, said armature assembly being pivoted at its center of gravity on a torsion angle pivot, a pair of electromagnets wound on saturable cores and positioned on opposite sides of said ferromagnetic slug, said electromagnets being adapted to be connected in parallel with a source of alternating current, a pair of diodes one of which is connected in series with each of said electromagnets to polarize said electromagnets and thereby cause them to be alternately energized by said alternating current, and a pair of stationary contacts positioned on opposite sides of said contacting member, each of said stationary contacts comprising a pair of resilient wire contacts adapted to bealternately engaged and disengaged by said contacting member as said ferromagnetic slug is alternately attracted to said electromagnets.

5. An electrical switching apparatus comprising, in combination, a rigid armature assembly, said armature assembly comprising a hollow tubular member carrying at one end a at slug of ferromagnetic material and carrying at its other end a contacting member, said armature assembly being pivoted at its center of gravity on a torsion angle pivot, a pair of saturable electromagnets positioned on opposite sides of said ferromagnetic slug and adapted to be connected in parallel with a source of alternating current, a pair of diodes one of which is connected in series with each of said electromagnets to cause the alternate energization by said current and thereby the vibration of said armature assembly at the frequency yof said alternating current, and a pair of resilient contacts positioned on opposite sides of said contacting member and adapted to be alternately engaged and disengaged by said contacting member as said armature assembly vibrates.

6, An electrical switching apparatus comprising, in combination, a lightweight rigid armature assembly, said armature assembly comprising a hollow tubular mem:

ber carrying at one end a flat slug of ferromagnetic material and carrying at its other end a contact, said armature assembly being pivoted at its center of gravity on a torsion angle pivot, a pair of saturable electromagnets positioned on opposite sides of said ferromagnetic slug and adapted to be connected in parallel with a source of alternating current, a pair of diodes one of which is connected in series with each of said electromagnets and poled to cause the alternate energization of said electromagnets by said current and thereby the vibration of said armature assembly at the frequency of said alternating current, and a pair of low mass resilient stationary contacts positioned on opposite sides of said armature assembly contact and adapted to be alternately engaged and disengaged by said contact armature assembly as said armature assembly vibrates.

7. Apparatus as specified in claim 6 wherein each of Said pair of resilient stationary contacts comprise a pair of shaped wire contacts clamped adjacent to each other in a relatively rigid member, which member is adjustable relative to the Contact on said armature assembly.

8. An electrical switching apparatus comprising, in combination, a lightweight rigid armature assembly, said armature assembly comprising a hollow tubular member carrying at one end a tlat T-sliaped slug of ferromagnetic material and at the other end a contacting member, said armature assembly being pivoted at its center of gravity on a torsion angle pivot, the center of gravity of said assembly being nearer to said ferromagnetic slug than to said contacting member, a pair of electromagnets wound on saturable cores and positioned on opposite sides of said ferromagnetic slug, said electroniagnets being adapted to be connected in parallel with a source of alternating current, a pair of diodes one of which is connected in series with each of said etectromagnets to polarize said electro-magnets and thereby cause them to be alternately energized by said alternating current, and a `pair of stationary contacts positioned on opposite sides of said contacting member, each of said stationary contacts comprising a pair of resilient wire contacts adapted to be alternately engaged and disengaged by said contacting member as said ferromagnetic slug-is alternately attracted to said electromagnets, said stationary contacts being further adapted to be adjusted in position relative to tne contacting member on said armature assembly.

9. 'double throw, double pole synchronous switch comprising in combination, a pair of rigid balanced armatures pivoted at their centers of gravity on frictionless pivots, one end of one of said pair of armatures being disposed between a tirst pair of saturating electromagnets, one end of the other of said pair of armatures being disposed between a second pair of saturating electromagnets, means f r alternately supplying unidirectional electrical energy to respective ones of each of said rst and second pairs of electromagnets and thereby to alternately attract to said respective ones of each of Said first and second pairs of electromagnets said ends of said armatures, each of said arma* .ures carrying on its other end a contact, a lirst pair of stationary contacts mounted adjacent to the contact on the end of one of said armatures, and a second pair of stationary contacts mounted adjacent to the contact on the end of the other of said armatures, said armature contacts being adapted to. alternately engage and disengage respective ones of said pairs of contacts as the other end of said armatures are alternately attracted to said electromagnets.

10. Apparatus as speci'ed in claim 9 wherein each of said stationary contacts comprises a pair of shaped resilient ivi-re contacts.

11. Apparatus as speciiied in claim l wherein the stationary Contact wire pairs are clamped in a relatively rigid member.

12. A double pole double throw synchronous switch comprising, in combination, a pair of rigid balanced armatures pivoted at their centers of gravity on torsion angle pivots, each of said armatures comprising a thin walled tube carrying at one end a flat slug of ferromagnetic material and at the other end a contacting member, a first pair of electromagnets, the ferromagnetic slug on one of said armatures being positioned in a gap between said rst pair of electromagnets, a second pair of electromagnets, the ferromagnetic slug on the other of said armatures being positioned in a gap between said second pair of electromagnets, means for alternately supplying unidirectional electrical energy to respective electromagnets and each of said pairs of electromagnets to cause the attaraction to said magnets of said slugs as said magnets are alternately energized, a contact block, a first pair of contacts mounted in said block adjacent the contacting member on one of said armatures, a second pair of contacts mounted in said block adjacent the contacting member on the other of said armatures, said contact block having means therein for adjusting each of said stationary contacts relative to the moving contacts of said armatures.

13. A double pole double throw synchronous switch comprising, in combination, a pair of lightweight rigid armature assemblies, each of said armature assemblies comprising a hollow tubular member carrying at one end a flat slug of ferromagnetic material and at its other end a contact, a torsion angle pivot for each of said armature assemblies, each of said armature assemblies being pivoted iat their center of gravity on said pivots, a first pair of saturable electromagnets positioned on opposite sides of one of said ferromagnetic slugs and adapted to be connected in parallel with a source of alternating current, a second pair of saturable electromagnets positioned on opposite sides of the other of said ferromagnetic slugs and also adapted to be connected in parallel With said source of alternating current, a pair of diodes,

one of said diodes `being connected in series with one of each of said pairs of electromagnets, the other of said diodes being connected in series with the other one of each of said pairs of electromagnets, said diodes being poled to cause the alternate energization of said electromagnets by said current and thereby the vibration of said armature assembly at the frequency of said alternating current, a rst pair of low mass resilient stationary contacts positioned on opposite sides of one of said armature assembly contacts and adapted to be alternately engaged and disengaged by said armature assembly as said armture assembly vibrates, a second pair of low mass resilient stationary contacts positioned on opposite sides of the other armature assembly contacts and adapted to be alternately engaged and disengaged by said other armature assembly when said other armature assembly vibrates, means connecting one of said first pair of stationary contacts on one `of said second pair of stationary contacts, and means connecting the other one of said iirst pair of stationary contacts to the other one of said second pair of stationary contacts.

14. Apparatus as specified in claim 13 wherein each of said resilient stationary contacts comprises a pair of shaped wire contacts clamped adjacent to each other in a relatively rigid member, which member is adjustable relative to the contact on the associated armature assembly.

References Cited in the le of this patent UNXTED STATES PATENTS 1,265,354 Merslion May 7, 1918 1,355,524 Atherton Oct. 12, 1920 2,790,129 Barnes Apr. 23, 1957 2,850,593 Hoover et al. Sept. 2, 1958 

